Construction of Escherichia coli cell factories / 生物工程学报

As an important model industrial microorganism, Escherichia coli has been widely used in pharmaceutical, chemical industry and agriculture. In the past 30 years, a variety of new strategies and techniques, including artificial intelligence, gene editing, metabolic pathway assembly, and dynamic regulation have been used to design, construct, and optimize E. coli cell factories, which remarkably improved the efficiency for biotechnological production of chemicals. In this review, three key aspects for constructing E. coli cell factories, including pathway design, pathway assembly and regulation, and optimization of global cellular performance, are summarized. The technologies that have played important roles in metabolic engineering of E. coli, as well as their future applications, are discussed.

Modulation of isoprenoid gene expression with multiple regulatory parts for improved beta-carotene production / 生物工程学报

Strong promoters might not be optimal to obtain maximum metabolic flux towards desired products, whereas modulating gene expression with multiple regulatory parts is an option to obtain optimal expression strength. Therefore, we assessed the difference of impact on beta-carotene production between modulating isoprenoid gene expression with multiple regulatory parts and strong promoter, to improve beta-carotene production through combined modulation of essential isoprenoid genes. Eight isoprenoid genes were modulated with six artificial regulatory parts having a wide range of strengths to assess their effects on beta-carotene production. Optimal strength for each isoprenoid gene expression was identified, leading to 1.2 to 3.5-fold increase in beta-carotene production. In contrast to previous reports, our work suggests that modulating dxr, ispG and ispH genes with appropriate strengths increase beta-carotene production. Beta-carotene yield reached 17.59 mg/g after combined modulation of dxs and idi genes, 8-fold higher than that of the parent strain. Modulating gene expression with multiple regulatory parts was better than strong promoter, providing a new gene modulation strategy for targeted biosynthesis.